MySQL获取所有分类的前N条记录
SELECT A1.* FROM stock_market AS A1 INNER JOIN (SELECT A.code,A.date FROM stock_market AS A LEFT JOIN stock_market AS B ON A.code = B.code AND A.date <= B.date GROUP BY A.code,A.date HAVING COUNT(B.date) <= 370 ) AS B1 ON A1.code = B1.code AND A1.date = B1.date ORDER BY A1.code,A1.date DESC
select a1.* from stock_market a1 inner join (select a.code,a.date from stock_market a left join stock_market b on a.code=b.code and a.date<=b.date group by a.code,a.date having count(b.date)<=2 )b1 on a1.code=b1.code and a1.date=b1.date order by a1.code,a1.date desc
select a.* from stock_market a where 2 > (select count(*) from stock_market where code = a.code and date> a.date) order by a.code,a.date
select a.* from stock_market a where exists (select count(*) from stock_market where code = a.code and date > a.date having Count(*) < 2) order by a.code